Method of and apparatus for preparing molds for casting



June 24.. 1924. 1.499207 R. L. FOLSOM METHOD OF AND APPARATUS FOR PREPARING MOLDS FOR CASTING Filed A112. 11, 1922 2 Sheets-Sheet l IM/E/VTOR RL. Folsom.

June 24, 924- 1,499,207

R. L. FOLSOM METHOD OF AND APPARATUS FOR PREPARING MOLDS FOR CASTING Filed Aug. 11 1922 2 Sheets-Sheet 2 WITNESSES IIVVENTOR R Z 1 025027 4TTORNEV8 Patented June 24, 1924-.

as e? EFICE.

RALPH L. FOLSOM, OF SALT LAKE CITY, UTAH.

IIIETHO'D OF AND APPARATUS FOR PREPARING MOLDS FOR CASTING.

Application fil'ed August 11, 1922. Serial No. 581,211.

To all whom it may concern:

Be it known that I, RALPH L. FoLsoM, a citizen of the United States, and a resident of Salt Lake City, in the county of Salt Lake and State of Utah, have invented certain new and useful Improvements in Methods of and Apparatus for Preparing Molds for Casting, of which the following is a specification.

This invention relates to a method of and apparatus for preparing molds for casting.

The present invention is particularly adapted for preparing molds utilized for casting porcelain or metal teeth or pieces thereof used in the profession of dentistry. The invention has for its object to provide a method and apparatus for the character specified whereby the wax usually employed for forming the pattern of the object to be cast may be washed or dissipated from the mold in which the same is invested in such a manner that the carbonization, contraction or disintegration of the mold is obviated and thereby produce a mold with a cavity for casting purposes which truly conforms to the outline and dimensions of the wax pattern.

Other objects will hereinafter appear.

In carrying out the present invention a heater is provided which includes anenclosure in which a high and substantially con stant temperature may be maintained. A

wax pattern is inserted in a mold made of investment material and water and permitted to stand approximately four minutes. The mold is then placed in the enclosure of the heater and the heat causes the moisture in the material forming the mold to wash out the wax pattern in approximately two or three minutes. The mold is now ready for casting and may be removed from the heater and the cavity within the mold is ab solutely clean, that is, no carbonizationof the Walls thereof has taken place and neither has the mold expanded or contracted.

A form of heater which may be utilized in practicing the present invention is shown in the accompanying drawings, in which:

Figure 1 is a view in side elevation of the heating apparatus or unit.

Figure 2 is a vertical transverse sectional view of the same.

Figure 3 is a perspective view of the heating element employed in the heating apparatus.

Figure i is a horizontal sectional view of the heating apparatus taken substantially on the line 44 of Figure 2.

Figure 5 is an enlarged fragmentary view in side elevation of the upper portion of the heating unit or apparatus.

Figure 6 is a perspective view of an insulating tube employed for protecting the wires extending witl in the apparatus to the heating element.

Figure 7 is a group view showing in per spective themold support and prongs for lifting the same.

Figure 8 is a detailed perspective View of a supporting means for the insulating tube protecting the conductor wires shown in Figure 6.

Referring to the drawings more particularly, the apparatus may consist in a supporting frame, comprising a plurality of uprights or legs L, preferably three in number, each of which is secured at a point adjacent its lower end to a ring R. The legs L may be secured to a ring R in each instance by means of a screw as at 10. Each leg L is bent to provide the upper portion 11, the lower portion 12, and an intermediate portion 13, the upper and lower portions being disposed vertically, whileithe interjmediate portion is disposed substantially horizontally. The upper portions 11 of the legs L have arranged thereon in superposed relation a multiplicity of annular plates P, each plate P being made of sheet metal. The upper portions of the legs 12 are extended through the sheets and the annular plates P are held in spaced relation with each other by meansof' washers 15, said washers encircling the different leg portions 11, and a washer being interposed between each of the annular plate members P. The inner peripheries of the annular plate members P will provide a tubular opening adapted to accommodate the cylindrical perforated member S. The member S is seated upon the supporting plate 15, said supporting plate'being spaced from the a11- nular plate members P by suitable washers 16, Figure 2. The leg portions ll extend through suitable openings provided in the plate 15. Thisplate is held from downward movement by the horizontal sections or portions 13 of the legs L. p

The heating element, shown in Figure 3, consists ina tubular casing which is made of suitable insulating material, such as porcelain or thelilxe, and upon which there is positioned eally shown in Figure 'lati-ng material such as porcelain or the like.

of these wires.

a winding or resistance wire WV. The winding N terminates at each end to provide a bare exterior space 16 at each end of the tube C. The supporting plate 15 is provided with a central opening adapted to receive the lower end portion of the tube O, and suitable insulating means is interposed between the winding W and the plate 15' as at 17. A cap plate 18 is. provided having a central opening adapted to receive the upper end portion 16 of the tube G. A sheet of insulating material 19 is interposed between the cap plate 18 and upper end of the resistance wire winding W. The cap plate 18 is also provided with suitable openings to receive the upper ends of the legs L, and upon the upper end of each leg L there is threaded a nut 20 whereby the different elements carried by said legs may be clamped and secured together. Preferably the outer edge of the cap plate 18 is turned downwardly as at 21. The cap plate 18 is preferably nickel plated in order to lend to the appearance of the apparatus.

The different annular plates P are also provided with registering openings adapted to receive a tube 22, said tube being specifi- 6 and made of insu- This tube is supported by a block 28, said block being specifically shown in Figure 8 of the drawings and as shown is formed with a transverse bore or opening 24: and with a pair of prongs or extensions 25 upon each side thereof. The block is also formed with a nipple 26 adapted to be received within the tube 22. The block 23 is supported by a w1re or the like as at 25, said wire having its ends secured to a pair of legs L as at 26. The block 23 may be secured to the wire 26 in any suitable manner, not shown. A flexible cord 27 may be extended through the block 23 and the conductor wires 28 of said cord passed upwardly and into the tube '22, the nipple 26 being of a diameter to permit the passage Also each'wire 28 may be passed between a pair of the extensions 25 in order to hold the same in One of the wires may be connected with the lower terminal of the resistance winding W as at 29, while the other wire may be connected with the upper terminal of the resistance wire N as at 29, Figure 5.

In Figure 6, M indicates generally a mold retainer or support which consists in a cylindrical shell having its lower I posed depressions 31, and each depression being provided with an opening suspending the moldretainer or holder M within the heating element is provided a pair of tongs generally indicated by the its position.

end portion filled with plaster of Paris orthe like as left which agrees closely to the .32. For

reference character T', said. tongs preferably consisting in a continuous strand of resilient wire bent to provide one or more convolutions 33 at a point central to the length-of the wire, and then the portions 3i existing upon each side of the convolution 33 being crossed as at 35 and provided with a bow portion 36 forward each other. Each bow portion in a downwardly extending portion. 31 which in turn terminates in an inwardly extending section or portion 38 adapted to form tooth or projections which will e tend into an opening 32 of the mold container or holder M.

In the practise of the present invention, the pattern is made of wax in the usual manner and properly invested in a mold. The mold should be made of moldine, or a like material, and a predetermined amount of water. the quantity of water being suiiicientto give the mold the desired plasticity for easy 36 terminates forming. The mold and pattern are now permitted to set three or four minutes and then may be placed in the top of the mold carrier M. Previous to this the electric current should be permitted to pass through the re sistance winding TV of so that the interior of the core C is heated to high degree. The tongs T may now be used for lifting the mold container M for lowering the same into the top of the tubular core C, as illustrated in Figure 1 'of the drawings; vVhen inserting a mold, the same has yet a certain amount of moisture therein and when the mold is brought within the tube C the moisture will be driven from the mold and will wash out the wax pattern in a thorough manner and leave the cavity formed by the pattern clean and ready for receiving metal or porcelain to form a casting. The purpose of the annular plates 1? is to the point of crossing the heating elements to provide a radiating means for the heating element and thus maintain a uniform maximum temperature. The perforated member Salso aids in this purpose and furtlier enables a compact and durable structure. During the time of heating the mold the tongs T may. be laid upon the heating apparatus, as illustrated in Figure 1, and then the mold retained in its suspended position withinthe tubular core C.

The inoldshould be formed which'will not contractor expand. under heat to any'appreciable extent, and by reing method heretofore described a cavity is of the original pattern; 7

While I have shown the particular apparatus by which my invention may be prac tised, it is to be understood that I am aware of the fact that the construction, combination and arrangement of V changed by those skilled the art without of a material dimens ons parts may be departing from the spirit of the invention as indicated by the appended claims.

I claim:

1. A methodv of forming molds of the character specified Which consists in investing a pattern or mold adapted to be dissipated by the action of moisture and heat in a mold and then subjecting the pattern to a high heat With moisture therein.

2. A method of forming molds of the character specified Which consists in. investing a pattern or mold adapted to be dissipated by the action of moisture and heat in a mold and then subjecting the pattern to a high heat With moisture therein for a predetermined interval.

3. A method for producing molds which comprises the investing of a pattern and an expansive fluid in a mold, and then submitting the same to heat whereby to permit the expansive fluid to Wash the pattern from said mold.

4-. A method of forming molds of the character described consisting in forming a mold made of material adapted to retain moisture then investing in the mold a pattern of Wax and then placing the mold in a heated chamber for a predetermined interval.

5. A method of forming molds of the character described which consists in forming a mold of moldine mixed With Water then investing in said mold a pattern of Wax and then placing the mold and pattern in a highly heated chamber.

RALPH L. FOLSOM. 

